Rates of uptake and metabolism of indole‐3‐acetic acid and 2,4‐dichlorophenoxyacetic acid by cultured leaf segments at different stages of development in wheat

Abstract

Immature leaf tissue of Triticum timopheevi Zukh. responded to supplied auxin and showed cell division in culture. The rates of uptake and of metabolism of indole‐3‐acetic acid and 2,4‐dichlorophenoxyacetic acid by such tissues were measured and compared with those of mature auxin‐unresponsive tissue. The purpose of these experiments was to determine whether or not the concentration of auxin in cultured mature tissue was a factor limiting the cell division response to auxin. The data indicate that neither alterations in rates of uptake nor alterations in rates of metabolism could explain the loss of responsiveness to auxin which apparently occurs during cell differentiation. The results are discussed in the context of the view that changes in cell sensitivity to growth substances and not only the concentration of these compounds, play an important role in plant growth and development.